Brushless motor integrated pump

ABSTRACT

A brushless motor integrated pump may include a brushless motor having a rotary shaft, a rotor axially mounted on the rotary shaft, a stator disposed around the rotor, a motor case forming a part of a case body and in which the rotor and the stator are accommodated, a motor cover covering the motor case with the rotary shaft penetrating through and protruding from an opening of the motor case, and low and high pressure-side gear pumps sharing the rotary shaft as a driving source and accommodated in a multistage manner inside a pump cover disposed on a surface of the motor cover to form the case body with the motor case. A low-pressure-side outlet may be formed in a pressurizing space communicated with a high-pressure-side outlet formed in the pressurizing space, in which a working medium may be introduced from the low-pressure-side inlet to flow, in order, into the low and high pressure-side gear pumps and may be pressurized, introduced into the motor case via a connection port which may be a high-pressure-side outlet formed in the motor cover, and caused to flow out from a case body outlet formed in the motor case. Low and high pressure outflow paths may be provided in which the low pressure outflow path may be communicated with the low-pressure-side outlet of the low-pressure-side working medium discharged from a pressurizing space of the low-pressure-side gear pump, or the high-pressure-side inlet of the high-pressure-side gear pump, to cause the low-pressure-side working medium to flow out from the low-pressure-side outlet of the low-pressure-side gear pump formed in the pump cover, and the high pressure outflow path may discharge the high-pressure-side working medium from the case body outlet formed in the motor case and discharged from the pressurizing space of the high-pressure-side gear pump. The pump may further have a connection passage including a check valve that may open the low and high pressure-side outflow paths toward the low-pressure-side outflow path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2018-177937, filed on Sep. 21, 2018, the contents of which are herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a brushless motor integrated pumpincluding a gear pump for pumping a working medium of a waste heatrecovery system, such as a Rankine cycle, and a motor for sharing arotary shaft with the gear pump and applying a driving force to the gearpump. More particularly, the present invention relates to a gear pumpincluding a plurality of rotary pumps.

BACKGROUND

Recently, a brushless motor integrated pump in which a brushless motorshares a rotary shaft with a gear pump to pump a working medium or thelike of the waste heat recovery system is provided and achieves highefficiency and high durability, as disclosed in JP 2016-101042 A.

The brushless motor integrated pump includes a rotor which is axiallymounted on the rotary shaft of the brushless motor and a stator disposedaround the rotor, and the rotor and the stator are accommodated in amotor case constituting a part of a case body. An opening of the motorcase is covered by a motor cover and the rotary shaft penetrates throughand protrudes from the opening of the motor case. A gear pump thatshares the rotary shaft of the brushless motor is installed on thesurface of the motor cover and accommodated inside a pump cover thatforms a case body with the motor case. A working medium is introducedfrom an inlet formed in the pump cover via a connection port, whichfunctions as an outlet of the gear pump formed in the motor cover, intothe motor case, and then caused to flow out from the outlet formed inthe motor cover.

Meanwhile, there have been cases where a desired high-pressure-sideworking medium cannot be obtained with one rotary pump, or two-systempressure sources of, for example, a low pressure working medium and ahigh pressure working medium are necessary as in the breaking apparatus,e.g., for anti-slipping. In these cases, two gear pumps sharing onerotary shaft to discharge different working media of low pressure andhigh pressure and being arranged in the direction of the rotary shaftare disclosed in, for example, JP 2000-161243 A and JP 2014-510864 A.

Therefore, it is conceivable to apply the brushless motor integratedpump to these two-system gear pumps.

However, the multistage gear pumps disclosed in JP 2000-161243 Adescribed above include the two-system gear pumps arranged apart fromeach other, so that it is necessary to extend the outlets from thetwo-system low-pressure and high-pressure gear pumps separately to thebrushless motor. Therefore, it is extremely difficult to integratingindividual gear pumps, which are separated from each other, with onebrushless motor. Further, for example, when the low-pressure gear pumpis continuously used for the working medium and the high-pressure gearpump is integrated with the motor, the high-pressure-side gear pumpshould be driven continuously at a predetermined rotation number evenwhen, for example, the working medium from the low-pressure-side gearpump is used, or the motor is not cooled, which is less economical.Indeed, there is a problem that the maximum pressure should be achievedby the high-pressure gear pump.

Meanwhile, in the gear pump disclosed in JP 2014-510864 A, thelow-pressure gear pump of the two-system gear pumps has its outletconnected to the inlet of the high pressure pump, so that the brushlessmotor integrated pump can easily be adapted to the two-system gearpumps. Although a high pressure working medium can be obtained by thetwo-system gear pumps, a low pressure working medium, if necessary, isobtained by depressurizing the high pressure working medium dischargedfrom the high-pressured outlet, which causes an economic loss.

SUMMARY

The present invention relates to a brushless motor integrated pump thatshares a rotary shaft with gear pumps and integrally includes a motorfor applying a driving force to the gear pumps. In particular, abrushless motor includes two-system rotary pumps as gear pumps to whichthe gear pumps are integrated to share the rotary shaft and achieve abrushless motor integrate pump having a small size and excellent coolingability. Such a brushless motor integrated pump can achieve highefficiency and high durability and can select and use at least one ofthe low-pressure-side working medium and the high-pressure-side workingmedium.

In order to solve the above problem, the present invention provides abrushless motor integrated pump including a rotor axially mounted on arotary shaft of a brushless motor and a stator disposed around therotor, the rotor and the stator accommodated in a motor case that formsa part of a case body, a motor cover covering the motor case with therotary shaft penetrating through and protruding from an opening of themotor case, a low-pressure-side gear pump and a high-pressure-side gearpump that share the rotary shaft of the brushless motor as a drivingsource and are accommodated in a multistage manner inside a pump coverwhich is disposed on a surface of the motor cover to form the case bodywith the motor case, and a low-pressure-side outlet of thelow-pressure-side gear pump formed in a pressurizing space communicatedwith a high-pressure-side outlet of the high-pressure-side gear pumpformed in the pressurizing space, in which a working medium isintroduced from the low-pressure-side inlet provided in the pump coverto flow into the low-pressure-side gear pump and the high-pressure-sidegear pump in this order and is pressurized, introduced into the motorcase via a connection port which is a high-pressure-side outlet of thehigh-pressure-side gear pump formed in the motor cover, and caused toflow out from a case body outlet formed in the motor case, the brushlessmotor integrated pump includes a low pressure outflow path provided forthe low-pressure-side working medium and a high pressure outflow pathprovided for the high-pressure-side working medium, in which the lowpressure outflow path is communicated with the low-pressure-side outletof the low-pressure-side working medium discharged from a pressurizingspace of the low-pressure-side gear pump, or the high-pressure-sideinlet of the high-pressure-side gear pump, to cause thelow-pressure-side working medium to flow out from the low-pressure-sideoutlet of the low-pressure-side gear pump formed in the pump cover, andthe high pressure outflow path discharges the high-pressure-side workingmedium from the case body outlet formed in the motor case and dischargedfrom the pressurizing space of the high-pressure-side gear pump, and aconnection passage including a check valve that opens thelow-pressure-side outflow path and the high-pressure-side outflow pathtoward the low-pressure-side outflow path.

Further, in the embodiment of the present invention, the check valveincluded in the connection passage is an electromagnetic valve, so thatthe working medium of a desired pressure can be reliably obtained.

Further, the flow rate of the low-pressure side gear pump is madesmaller than the flow rate of the high-pressure side gear pump to obtainthe low pressure working medium and the high pressure working medium,respectively, even when the rotary shaft is shared.

According to the embodiment of the present invention, the brushlessmotor integrated pump includes the motor that shares the rotary shaftwith the two-system integrated gear pumps to apply driving force to thegear pumps, achieves high efficiency and high durability, and, inparticular, can choose and use at least one of the low-pressure-sideworking medium and the high-pressure-side working medium.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical sectional view of a brushless motor integrated pumpaccording to a preferred embodiment of the present invention and is alsoan explanatory view illustrating a flow path of a working medium;

FIGS. 2A and 2B are explanatory views each illustrating an outline of ahigh-pressure-side gear pump in FIG. 1;

FIG. 3 is a graph illustrating a relationship between the flow rate of ahigh-pressure-side pump and the flow rate of the low-pressure-side pump,both pumps rotating at the same rotation number, to obtain asystematically required flow rate range of both pumps;

FIG. 4 is a graph illustrating a relationship between the pump rotationnumber and the flow rate for the high-pressure-side gear pump and thelow-pressure-side gear pump obtained from the system required flow raterange, as illustrated in FIG. 3, to set a combination of the flow rateof the high-pressure-side gear pump and the low-pressure-side gear pump;and

FIG. 5 is a graph illustrating a relationship between the rotationnumber and the flow rate of an ideal flow rate and an actual measuredvalue of the pump of the gear pumps.

DETAILED DESCRIPTION

A preferred embodiment of the present invention will be described indetail below with reference to the accompanying drawings.

FIGS. 1, 2A, and 2B illustrate a brushless motor integrated pumpaccording to a preferred embodiment of the present invention. A workingmedium 10 is introduced into a case body 1, which includes a pump cover2, a motor cover 3, and a motor case 4, from a cover body inlet 21formed in the pump cover 2. The working medium 10 is made to flow to acase body outlet 41 formed in the motor case 4 via a connection port 31formed in the motor cover 3. A direct current (DC) brushless motor 7shares a rotary shaft 6 with a two-system gear pumps including alow-pressure-side gear pump 5 a and a high-pressure-side gear pump 5 b,which are accommodated inside the pump cover 2. A straightening member 8is disposed between the motor cover 3 and the motor case and connectedto the connection port 31. A control unit 9 for controlling the rotationnumber of the brushless motor 7 is disposed outside the case body 1.

The brushless motor 7 includes a stator 71 and a rotor 72, and therotary shaft 6 supported by a bushing 61. The stator 71 includes astator core 711 and a coil 712. Space outside the coil 712 wound arounda notch portion 713 of the stator core 711 functions as a working mediumchannel 714 through which the working medium 10 passes.

Further, at least a part of the end face of the stator core 711 isformed not to pass through a gap between the outer peripheral surface ofthe motor case 1 and a step portion 42, or pass through the gap to allowa smaller flow rate compared to the working medium passage 714.

The rotor 72 includes a substantially cylindrical rotor core 721, whichis axially mounted on the rotary shaft 6, and a magnet 722 fitted to therotor core 721.

It is particularly preferable that the rotor core 721 is provided with aplurality of through holes (not illustrated) axially symmetrically topenetrate through both end surfaces to achieve weight reduction and costsaving.

Further, the brushless motor integrated pump of the present embodimentincludes, at the outside of the case body 1 which is configured to beliquid tight, a power supply (not illustrated) for supplying an electriccurrent to the coil 712 of the stator 71 of the brushless motor land thecontrol device 9 for controlling the rotation number of the rotor 72 ofthe brushless motor 7. Therefore, it is possible to prevent a failuresuch as breakage of the parts by immersing the parts in the workingmedium 10 that fills the case body 1.

Meanwhile, the two-system gear pumps 5 a and 5 b, which are accommodatedinside the pump cover 2, are conventional inscribe gear pumps, asillustrated in, for example, FIGS. 2A and 2B, that share the rotaryshaft 6 protruding on the top surface of the motor cover 3 of thebrushless motor 7 and are accommodated in a multistage manner in theaxial direction of the shaft. In each gear pump 5 a (5 b), an inner gear51 a (51 b) axially mounted on the rotary shaft 6 and an outer gear 53 a(53 b) inscribed in an outer bearing 52 a (52 b) disposed around theinner gear 51 a (51 b) are installed in a partially meshing state.Meanwhile, a crescent-shaped crescent seal 54 a (54 b) is disposedbetween the inner gear 51 a (51 b) and the outer gear 53 a (53 b) forpartitioning a high-pressure-side from a low-pressure-side. The workingmedium 10 is suctioned from a low-pressure-side inlet 55 a and ahigh-pressure-side inlet 55 b to move to a suction-side space 56 a (56b), which is formed between the inner gear 51 a (51 b) and the outergear 53 a (53 b) across the crescent seal 54 a (54 b). The workingmedium 10 reaches a pressurizing space 57 a (57 b) where the workingmedium 10 is pressurized and discharged from a low-pressure-side outlet58 a and a high-pressure-side outlet 58 b.

In particular, in the present embodiment, the low-pressure-side gearpump 5 a and the high-pressure-side gear pump 5 b are formed in amultistage manner in the axial direction, and the low-pressure-sideoutlet 58 a of the low-pressure-side gear pump 5 a is communicated withthe high-pressure-side gear inlet 55 b of the high-pressure-side gearpump 5 b.

Further, the flow rate of the low-pressure-side gear pump 5 a is smallerthan the flow rate of the high-pressure-side gear pump 5 b. With respectto this point, in the present embodiment, since the flow rate of thelow-pressure gear pump 5 a uses the common rotary shaft 6 with thehigh-pressure gear pump 5 b, it is difficult to mutually change therotation number. Alternatively, for example, it is possible to mutuallychange the diameter of 51 a (51 b) to change the volume ofpressurization space.

Since the present embodiment is configured to drive thelow-pressure-side gear pump 5 a and the high-pressure-side gear pumps 5b using the common rotary shaft 6, the pumps come to rotate at the samerotation number, and the flow rate required by the system needs to beset from the discharge amount of each pump 5 a, 5 b.

FIG. 3 illustrates a system required range of the flow rate of thehigh-pressure-side gear pump 5 b according to the relationship betweenthe flow rate QH of the high-pressure-side gear pump 5 b and the flowrate QL of the low-pressure-side gear pump 5 a. FIG. 4 illustrates, inthe system required range of FIG. 3, a sum of the flow rate QH of thehigh-pressure-side gear pump 5 a and the flow rate QL of thelow-pressure-side gear pump (QH+QL), and a relationship between the pumprotation number and the flow rate for the low-pressure-side gear pump 5a and the high-pressure-side gear pump 5 b. For example, if the flowrate QH of the high-pressure-side gear pump 5 b illustrated in FIG. 3 is“a”, the flow rate of the low-pressure-side pump 5 b is determined froman intersecting point A of the system required flow rate (i.e., a sum(QH+QL) of the flow rate QH of the high-pressure-side gear pump and theflow rate OL of the low-pressure-side gear pump).

As can be seen from the relationship between the pump rotation numberand the flow rate in the ideal flow rate and the pump actual value inthe gear pump, the actual gear pump includes an internal leakage whichneeds to be considered in determining the flow rate.

Disclosed in the present embodiment in communication between thelow-pressure-side outlet 58 a of the low-pressure-side gear pump 5 a andthe high-pressure-side inlet 55 b of the high-pressure-side gear pump 5b are a low pressure outflow path 11 for causing the low-pressure-sideworking medium 10 a to flow out from a cover body outlet 22 formed inthe pump cover 2, and a high pressure outflow path 12 for causing thehigh-pressure-side working medium 10 b to flow out from the case bodyoutlet 41 formed in the motor case 4. Further, a connection passage 14including a check valve 13 that opens toward the low pressure outflowpath 11 is provided to communicate the low pressure outflow path 11 withthe high pressure outflow path 12.

In the present embodiment that has been configured as illustrated inFIGS. 1, 2A, and 2B, when the brushless motor 7 is activated, thelow-pressure-side gear pump 5 a and the high-pressure-side gear pump 5b, which share the rotary shaft 6, operate in synchronization with eachother. Accordingly, the working medium 10 is suctioned inside from thecover body inlet 21 formed in the pump cover 2 by a negative pressuregenerated at the low-pressure-side inlet 55 a of the low-pressure-sidegear pump 5 a. The working medium 10 is then fed to and pressurized inthe pressurized space 57 a by meshing of the inner gear 51 a and theouter gear 53 a, and pumped to the low-pressure-side outlet 58 a as thelow-pressure-side working medium 10 a.

The low-pressure-side outlet 58 a of the low-pressure-side gear pump 5 ais connected to the high-pressure-side inlet 55 b of thehigh-pressure-side gear pump 5 b disposed on the brushless motor 7 side.The low-pressure-side working medium 10 a that has been pumped from thelow-pressure-side outlet 58 a of the low-pressure-side gear pump 5 a issuctioned inside from the high-pressure-side inlet 55 b of thehigh-pressure-side gear pump 5 b, and pressurized and pumped to thehigh-pressure-side outlet 58 b, as in the case of the low-pressure-sidegear pump 5 a.

The high-pressure-side outlet 58 b of the high-pressure-side gear pump 5b is connected to the connection port 31 formed between the motor cover3 and the motor case 4. The high-pressure-side working medium 10 bdischarged from the low-pressure-side outlet 58 b of thelow-pressure-side gear pump 5 b adjusts its direction by a straighteningmember 8 so as to flow from the connection port 31 in the same directionas the rotating direction of the rotor 72. Accordingly, thehigh-pressure-side working medium 10 b is introduced into the motor case4 and exchanges heat by cooling the brushless motor 7 through theworking medium path 714 (notch 713) and flow out from the case bodyoutlet 41 formed in the motor case 4. This suppresses heat generation ofthe coil 712 and reduces load from a drag caused by friction at thebearing or a pressure received from the high-pressure-side workingmedium 10 b, thus improving durability.

In the present embodiment, the low-pressure-side working medium 10 aflowing out from the cover body outlet 22 formed in the pump cover 2 andthe high-pressure-side working medium 10 b flowing out from the casebody outlet 41 formed in the motor case 4 are fed to the waste heatrecovery system (not illustrated) such as the well-known Rankine cycleused in the practice of the conventional art via the low pressureoutflow path 11 and the high-pressure-side flow path 12. The presentembodiment can be applied to an operating mechanism (not illustrated)that requires a two-system pressure source using the working media atdifferent pressures with one driving source, thus achieving an efficientuse of space and a labor-saving operation.

Further, in the present embodiment, the high-pressure-side workingmedium 10 b from the high pressure outflow path 12 out of the twosystems is obtained as a high pressure working medium pressurized by thelow-pressure-side gear pump 5 a and the high-pressure-side gear pump 5b.

Further, in the present embodiment, the two systems including the lowpressure outflow path 11 and the high pressure outflow path 12 areconnected by the connection passage 14 via the check valve 13, so thatthe present embodiment can be used as a supply source of the two-systemlow pressure-side working medium 10 b with one power source. Adjustingthe opening of the check valve can change the pressure of thelow-pressure-of working medium 10 a and the low-pressure-sidepressurizing of the low-pressure-side.

1. A brushless motor integrated pump comprising: a brushless motorhaving a rotary shaft a rotor axially mounted on the rotary shaft; astator disposed around the rotor; a motor case forming a part of a casebody and in which the rotor and the stator are accommodated; a motorcover covering the motor case with the rotary shaft penetrating throughand protruding from an opening of the motor case; a low-pressure-sidegear pump and a high-pressure-side gear pump that share the rotary shaftof the brushless motor as a driving source and are accommodated in amultistage manner inside a pump cover which is disposed on a surface ofthe motor cover to form the case body with the motor case; alow-pressure-side outlet of the low-pressure-side gear pump formed in apressurizing space communicated with a high-pressure-side outlet of thehigh-pressure-side gear pump formed in the pressurizing space, in whicha working medium is introduced from the low-pressure-side inlet providedin the pump cover to flow into the low-pressure-side gear pump and thehigh-pressure-side gear pump in this order and is pressurized,introduced into the motor case via a connection port which is ahigh-pressure-side outlet of the high-pressure-side gear pump formed inthe motor cover, and caused to flow out from a case body outlet formedin the motor case; a low pressure outflow path provided for thelow-pressure-side working medium and a high pressure outflow pathprovided for the high-pressure-side working medium, in which the lowpressure outflow path is communicated with the low-pressure-side outletof the low-pressure-side working medium discharged from a pressurizingspace of the low-pressure-side gear pump, or the high-pressure-sideinlet of the high-pressure-side gear pump, to cause thelow-pressure-side working medium to flow out from the low-pressure-sideoutlet of the low-pressure-side gear pump formed in the pump cover, andthe high pressure outflow path discharges the high-pressure-side workingmedium from the case body outlet formed in the motor case and dischargedfrom the pressurizing space of the high-pressure-side gear pump; and aconnection passage including a check valve that opens thelow-pressure-side outflow path and the high-pressure-side outflow pathtoward the low-pressure-side outflow path.
 2. The brushless motorintegrated pump according to claim 1, wherein the check valve includedin the connection passage is a solenoid valve.
 3. The brushless motorintegrated pump according to claim 1, wherein a flow rate of thelow-pressure-side gear pump is smaller than a flow rate of thehigh-pressure-side gear pump.
 4. The brushless motor integrated pumpaccording to claim 2, wherein a flow rate of the low-pressure-side gearpump is smaller than a flow rate of the high-pressure-side gear pump.